GasCap™Know before
you go.
Calculate fuel & cost before you pull up to the pump.
Fill up in the morning — fuel is denser when it's cool, so you get slightly more per gallon.
Know exactly how much gas you need — before you pull up.
With gas prices near record highs, know your exact fill-up cost before you swipe your card. No guessing. No overpaying.
Sign up today — first 30 days of Pro FREE
$2.99/mo after trial · No credit card · Cancel anytime
Free forever · Pro $2.99/mo · Lifetime $19.99 · See all plans ↓
Partnering with local businesses
Fill-Up Calculator
Set your tank, current level, and target fill — we'll tell you exactly what to pump and what it costs.
How to use
Current Fuel Level
1/64 tank step
Drag the handle · or tap anywhere on the arc
Sign in to use AI gauge scan and auto-detect your fuel level from a photo.
Fill Up To
Gas Price per Gallon
Tools & Insights
AI Fuel Advisor
Get personalized fuel-saving tips, trip estimates, and smart driving advice.
Stop guessing at the pump
GasCap™ solves the three most frustrating gas station moments.
Wondering if you have enough cash to fill up
✓ Know the exact cost before you swipe your card
Returning a rental car on empty — $12/gallon fees
✓ Calculate exactly how many gallons to buy first
No idea what you're spending on gas each month
✓ MPG trends and monthly spend tracked automatically
Everything you need to stop overpaying
Fuel calculator
Enter your tank level, pick a target fill, and get the exact gallon count and cost — in seconds.
Live gas prices
Real-time local prices from the U.S. EIA — auto-detected by location. Free with an account.
Works offline
Install it like an app. No signal? The calculator always works with your saved data.
MPG & spend tracking
Log every fill-up. See your efficiency trends, monthly spend, and fuel cost per mile.
AI fuel advisor
Ask anything — best fill strategy, octane grade, or how to improve your MPG.
PDF & CSV export
Export your fill-up history and fuel reports for personal finance or fleet records.
Renting a car? Never overpay at drop-off.
Rental companies charge up to $12/gal if you return empty. GasCap™ Rental Car Return Mode tells you exactly how many gallons to buy — and shows your exact savings vs. letting them fill it.
Toggle "🚗 Rental Car Return?" in the calculator above.
Who uses GasCap™
Daily Drivers
Know your fill-up cost every time. Budget your gas spend to the dollar.
Frequent Travelers
Use Rental Car Return Mode to skip the $12/gal refueling trap every trip.
Road Trippers
Plan your fuel budget stop by stop. Know costs before you leave the driveway.
Fleet Managers
Track fuel costs across your entire fleet. Export reports. Control spending.
Free
Forever — no catch
5.0★
Average rating
<2s
Typical calculation
📅 Next Drawing
July 5, 2026
$25 Visa · for June's entries
Luis L.
April 2026
A new winner is drawn every month. Create a free account to enter automatically.
Frequently Asked Questions
Plans & Pricing
Start free. Upgrade when you're ready. No surprises.
Free
No CC EverFull calculator · gas prices · offline PWA · no catch
- 1 saved vehicle
- Target Fill calculator
- By Budget calculator
- EV Charge calculator
- Rental Car Return Mode
- Trip Cost Estimator
- Station Comparison
- EPA vehicle database search
- Live gas price lookup
- Badge achievements
- Works offline (PWA)
Pro
Individuals & CouplesBilled monthly · cancel anytime
- Everything in Free
- Unlimited saved vehicles
- Fill-up logging & fuel history
- VIN photo scan
- Receipt photo scan (AI)
- AI Fuel Advisor (GPT-4o)
- Gas price drop alerts
- Monthly gas card giveaway entries
- Manual entry + auto spec lookup
- Engine type & tank size auto-detected
- MPG trending chart
- Fuel cost PDF export
- Monthly fuel budget tracker
- SMS fill-up reminders (coming soon)
- Referral rewards
- Priority support
Pro Lifetime
One-time paymentOwn GasCap™ Pro forever — no recurring charges
🏝️ Free getaway included
Buy Lifetime now and we'll send you a complimentary resort getaway certificate.
Hotel stay only — flights not included. The room rate is complimentary (no timeshare); you cover the nightly taxes & fees (vary by destination) plus your own travel. Must be 21+, live 100+ miles from your destination, and book 30+ days ahead. Full terms at RedeemVacations.com.
- Everything in Pro
- ⭐2× giveaway entries every month
- 🛡️Streak Shield — 1 grace day/month
- 🏅Lifetime Member badge
Just $19.99 once — about 7 months of monthly, then free forever. Most members choose Lifetime.
30-Day Money-Back Guarantee (Monthly plan)
If Pro doesn't save you more than $2.99 in your first month, email us and we'll refund your first payment — no questions asked.
Lifetime purchase is final
The $19.99 Lifetime plan is a one-time, non-refundable purchase. See our Terms of Service for details.
Know before
you pull up.
Start with 30 free days of Pro — then $2.99/mo, cancel anytime. Save your vehicles, track your MPG, and stop over-paying at the pump.
Start free — 30 days Pro included →Already have an account? Sign in